Modern vehicle-to-vehicle communication and vehicle-to-infrastructure communication (subsequently together called C2X) is frequently designed such that it works in the respective vehicle even without digital map material. In many cases, however, vehicles additionally use digital map material to improve the C2X functions, or digital maps are present for driver assistance systems and/or safety systems in the vehicle.
Irrespective of the C2X communication, attempts are made to improve the digital map material and hence also the reliability of driver assistance systems and safety systems in the vehicle.
The document WO 2009/56533 A1, which is incorporated by reference, discloses an assessment module for assessing data from a digital map for a vehicle, which assessment module takes measurement data from an ambient sensor system in the vehicle and/or takes map-inherent quality information as a basis for assessing data from the digital map and then transfers the assessment to a driver assistance system or a safety system in the vehicle. These systems then use the data from the digital map on the basis of the assessment.
The document DE 10 2007 003 147 A1, which is incorporated by reference, discloses a driver assistance system for a vehicle which takes a calculated level of map reliability as a basis for executing associated operations. In this context, the level of map reliability indicates the accuracy of map data in the neighborhood of the current position of the vehicle. The level of map reliability is determined by means of a complicated formula about the adjacent positions of the vehicle. This formula takes account of the positioning accuracy of the map data for the position of the vehicle, the change in data after a period of time has elapsed, and the ratio of the match between map information and the actual data.
The known devices or methods allow only an assessment of the data from existing digital maps, however. The conventional methods imperatively assume the presence of a digital map and/or of a local or global navigation system so as in each case to perform appropriate position-finding for the current position with respect to the digital map which is present in the vehicle. However, there are situations and applications which firstly do not imperatively assume a digital map, or a navigation system is not present or does not operate reliably. In such cases, the known methods cannot be used.